Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – Frequency of cyclic current or voltage
Patent
1990-01-22
1991-02-05
Tokar, Michael J.
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
Frequency of cyclic current or voltage
364485, G01R 2314
Patent
active
049908480
ABSTRACT:
A DTMF receiver (10) recognizes each of a plurality of multi-frequency tones, each tone centered on a predetermined standard frequency. Two digital bandpass filters (14, 16) each have four frequency bins, each frequency bin operating according to a recursive second-order transfer function for preferentially transmitting frequencies near the standard frequencies. Each frequency bin accumulates, for each of a plurality of sampling periods, respective spectral energy signals from the input signal. A temporal energy signal is derived from the spectral energy signals. For each bandpass filter (14,16), a time-domain test template generator (30) and a frequency-domain test template generator (34) are provided to generate time-domain and frequency-domain test templates. These test templates are input to an analyzer (38) that compares the templates against data-adaptive frequency-domain and time-domain reference templates.
REFERENCES:
patent: 4445177 (1984-04-01), Bratt
patent: 4455602 (1984-06-01), Baxter
patent: 4493027 (1985-01-01), Katz
patent: 4525780 (1985-06-01), Bratt
patent: 4833399 (1989-05-01), So
Barndt B. Peter
Comfort James T.
Sharp Melvin
Texas Instruments Incorporated
Tokar Michael J.
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